I am a bit new in domotica , i have a raspberry with a rfxtrx working well with kaku.Last week i bought a z-wave stick sr2, is it possible to use it at the same time with the rfxtrx.And cane i use this stick to turn on and off of my alarm system bosch easy serie.

Yes, you can use RFXCom and Z-Wave at the same time ... your domotica application should be able to handle this. The Bosch alarm is difficult to say, first google search doesn't seem to show the option to arm/disarm it remotely.